Multi-step subsidence inversion for rift basin lithospheric modeling
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Solution Overview
Problem
Conventional petroleum systems modeling approaches fail to accurately describe the evolution of rift basins due to inadequate consideration of different processes in lithospheric layers, particularly in modeling basal heat flow and lithospheric layer thickness variations over geological time.
Innovation Solution
A multi-step subsidence inversion method is employed to model lithospheric layer thickness through geological time, separately fitting upper mantle and crustal stretching factors to syn-rift and post-rift subsidence curves, and modeling thermal thickening of the upper mantle during the post-rift phase to accurately depict thickness variations and basal heat flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional single-step subsidence inversion is used to model lithospheric layer thickness, then the modeling process is simple and quick, but the accuracy and geological reasonableness of the results deteriorate due to inadequate consideration of different processes in crust and upper mantle layers
Solution Approach 1:
The patent divides the single-step subsidence inversion into two separate sequential steps: first inverting syn-rift subsidence to model crustal stretching, then inverting post-rift subsidence to model upper mantle stretching and thermal thickening. This segmentation allows each layer to be modeled with appropriate geological processes, improving accuracy while maintaining computational feasibility.
Solution Approach 2:
The patent performs the crustal stretching modeling as a preliminary action before upper mantle stretching modeling. By first determining the crustal stretching factor from syn-rift subsidence, the model establishes a foundation for the subsequent upper mantle inversion, ensuring that each modeling step builds on geologically consistent prior results.
2Productivity
If different stretching factors are applied to crust and upper mantle in a single fitting routine, then the modeling approach is computationally efficient, but the geological reasonableness deteriorates due to failure to consider different processes in lithospheric layers
Solution Approach 1:
The patent segments the modeling of different lithospheric layers into separate computational routines executed in sequence. Crustal stretching is modeled first using syn-rift subsidence data, then upper mantle stretching is modeled using post-rift subsidence data. This segmentation ensures each layer's unique geological processes are properly considered while maintaining computational efficiency through modular processing.
Solution Approach 2:
The patent performs crustal stretching modeling as a preliminary computational step before upper mantle stretching modeling. This preliminary action establishes the crustal component of lithospheric evolution, allowing the subsequent upper mantle inversion to focus specifically on mantle processes without the complexity of simultaneously fitting both layers.
3Device complexity
If thermal thickening of upper mantle is not modeled during post-rift subsidence, then the modeling process is simpler, but the accuracy of lithospheric layer thickness evolution deteriorates
Solution Approach 1:
The patent incorporates thermal thickening modeling as an integral part of the post-rift subsidence inversion process. By including thermal thickening in the upper mantle stretching model during post-rift phase, the patent accurately captures the evolution of upper mantle thickness without requiring separate complex thermal modeling steps.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach provides more geologically reasonable and accurate modeling of lithospheric layer thickness evolution and basal heat flow, improving the prediction of hydrocarbon reserves and optimizing oilfield operations by offering a more precise understanding of subsurface processes.
Implementation Method 1
modeling the thermal thickening of the upper mantle lithospheric layer of the subsurface formation during the post-rift subsidence
Implementation Method 2
during a syn-rift phase, the lithospheric layers are stretched and thinned
Implementation Method 3
during a post-rift phase, the lithospheric or upper mantle cools back to a roughly pre-rift thickness
Data Source
Figure 1
Figure 2A~2D
Figure 3
AI summary
A method, apparatus, and program product utilize a multi-step subsidence inversion to model lithospheric layer thickness through geological time for a rift basin in a subsurface formation.